Pressure release port for a walk-in freezer or the like

ABSTRACT

A pressure release port for a walk-in freezer or the like formed by an aperture extending through a wall of the freezer adjacent the walk-in door thereof. The aperture permits air flow between the atmosphere and the freezer interior to avoid the development of any pressure differential. An electric light bulb is mounted in the aperture to create heat in the aperture to minimize accumulation of moisture and frost from the air flowing through the aperture. Air filters are mounted on each surface of the freezer wall and extend across the aperture with the light bulb therebetween. The filters serve to clean the air and to provide resistance to the free flow of air through the aperture, thereby enhancing the heating effect of the light bulb. Each air filter is slidably mounted in an open-ended frame secured to the freezer wall surface to permit cleaning and replacement removal of the filters and to allow access to the light bulb.

United States Patent [191 Brown 1 Nov. 4, 1975 [75] Inventor: Edward A. Brown, Salisbury, NC.

[73] Assignee: W. A. Brown & Son, Inc., Salisbury,

221 Filed: Dec. 2, 1974 211 Appl. NO.Z 528,736

Primary ExaminerWilliam .l. Wye Attorney, Agent, or Firm-Richards, Shefte & Pinckney [57] ABSTRACT A pressure release port for a walk-in freezer or the like formed by an aperture extending through a wall of the freezer adjacent the walk-in door thereof. The aperture permits air flow between the atmosphere and the freezer interior to avoid the development of any pressure differential. An electric light bulb is mounted in the aperture to create heat in the aperture to minimize accumulation of moisture and frost from the air flowing through the aperture. Air filters are mounted on each surface of the freezer wall and extend across the aperture with the light bulb therebetween. The filters serve to clean the air and to provide resistance to the free flow of air through the aperture, thereby enhancing the heating effect of the light bulb. Each air filter is slidably mounted in an open-ended frame secured to the freezer wall surface to permit cleaning and replacement removal of the filters and to allow access to the light bulb.

5 Claims, 5 Drawing Figures US. Patent Nov. 4, 1975 Sheet 1 of2 3,916,643

US. Patent Nov. 4, 1975 Sheet 2 of2 PRESSURE RELEASE PORT FOR A WALK-IN FREEZER OR THE LIKE BACKGROUND OF THE INVENTION The present invention relates to a pressure release port for a walk-in freezer or the like, and more particularly to a pressure release port of the type used to permit air flow between the interior of the freezer and the atmosphere so as to avoid any significant pressure differential therebetween during the freezer cooling and defrosting cycles and when the freezer door is opened or closed.

Pressure release ports are not universally used in walk-in freezers because of the problems of heat transfer from free flow of air through the port and frost and moisture accumulation in the port and freezer due to condensation upon cooling of ambient air entering through the port. Ina currently used pressure release port arrangement intended to alleviate these problems a vertically disposed flat plate is pivoted in the port about a horizontal axis for free swinging. With this arrangement the plate normally hangs in a position substantially closing the port to resist free air flow that would produce frost or moisture condensation, but swings inwardly and outwardly to allow pressure equalizing air flow therethrough in response to air pressure differentials upon contraction of air in the freezer during the cooling cycles, upon expansion of the air in the freezer-during defrosting cycles, and upon opening and closing of the freezer door. To provide heat in the port to attempt to maintain the temperature of the air therein sufficiently elevated to prevent condensation that occurs when ambient air is cooled upon mixing with the cooler air from within the freezer, electrical heating coils are mounted on the plate. This arrangement, when it operates properly, is obviously better than having a completely open port, but it provides no resistance to air flow on opposite sides of the plate in and out of the port and the heating coils increase this air flow by heating the air. Further, this unhindered air flow dissipates the desired heating effect and, therefore, reduces the effectiveness of the heating coils to avoid frost and moisture condensation. Moreover, heating coils and relatively fragile and when broken or otherwise rendered non-operable there is no visible or other convenient way of detecting the defective condition until the frost and moisture accumulation becomes excessive.

In contrast, the present invention provides a pressure release port that permits adequate air flow while preventing accumulation of frost or moisture condensation and does so in a simple, effective, efficient and reliable manner.

SUMMARY OF THE INVENTION Briefly described, the pressure release port of the present invention is incorporated in a walk-in freezer or the like as an aperture extending through a wall of the freezer. An electric light bulb is mounted in the aperture with means for energizing the light bulb to create heat in the aperture for minimizing mositure and frost accumulation therein. An air filter extends across the aperture to clean air passing therethrough and to provide resistance to the free flow of air therethrough, thereby enhancing the heating effect of the light bulb.

Preferably the air filter is disposed across the aperture on one surface of the freezer wall in an openended frame secured to the wall surface, in which frame the filter is slidable to permit cleaning and replacement removal of the filter and access to the light bulb. In the preferred embodiment there are two air filters, each extending across the aperture on opposite wall surfaces with the light bulb therebetween, the filters thereby tending to confine air in the aperture for effective and efficient heating action by the light bulb to minimize frost and moisture condensation in the aperture.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a walk-in freezer in which the pressure release port of the preferred embodiment of the present invention is incorporated;

FIG. 2 is an enlarged elevational view of the pressure release port portion of the freezer of FIG. 1;

FIG. 3 is a horizontal sectional view taken along line 3-3 of FIG. 2;

FIG. 4 is a vertical sectional view taken along line 4-4 of FIG. 3; and

FIG. 5 is a vertical sectional view taken along line 55 of FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The pressure release port 10 of the preferred embodiment of the present invention is illustrated in the drawings as incorporated in a walk-in freezer F of the type used in food stores, markets, hospitals, schools, dairies or for similar purposes. The particular freezer F illustrated has walls W formed with metal sheet surfaces S and foamed urethane interior insulation 1, but the specific construction does not form a part of the present invention as it is adaptable as well to other materials, constructions and freezer types.

The pressure release port is formed by cutting through the freezer wall W in the space above the walkin door D to provide an aperture 12 extending through the wall W from the exterior to the interior of the freezer F. A rectangular frame 14 is secured in the aperture 12 to provide a neatly defined periphery for the aperture and to facilitate support for the base 16 of a light bulb socket 18 in one side wall 20 of the frame 14.

An electric light bulb 22 is removably supported in the socket 18 in horizontal disposition within the aperture 12 to create heat in the aperture upon energization of the bulb for minimizing moisture and frost accum ulation in the aperture.

The base 16 of the socket 18 is secured by screws 24 extending through the frame side wall 20 and threaded into the flange 26 of a first junction box 28 within the freezer wall W. A second junction box 30 is secured by a connector 32 to the first junction box 28 and extends laterally and outwardly therefrom to the exterior surface S of the freezer wall W at which it is covered by a plate 34 that is secured to brackets 36 on the second junction box 30 by screws 38. Electrical lead wires 40 extend from the socket 18 through the first junction box 28, connector 32, second junction box 30 and cover plate 34 from which the lead lines 40 extend to an electrical receptacle 42 mounted on the exterior of the freezer wall W above the door D. The receptacle 42 is connected through an electrical conduit 44 and switch 46 to a source of electricity for energization of the light bulb 22 in the aperture 12.

To clean the air passing through the aperture 12 and to provide resistance to the free flow of air therethrough so as to enhance the heating effect of the light bulb 22, air filters 48 are disposed on the exterior and interior wall surfaces S and extend across the aperture 12. These filters 48 are rectangular in shape and are slidably mounted in open-ended U-shaped frames 50 that are secured by rivets 52 to the wall surfaces S. The frames 50 have outwardly projecting intermediate flanges 54 spaced from the periphery of the aperture 12 and vertically projecting outer flanges 56 extending from the intermediate flanges 54 toward the aperture periphery to form with the intermediate flanges 54 and adjacent wall surface S filter retaining tracks that support the filters 48 across the aperture while allowing sliding removal of the filters from the open ends 58 of the frames 50 to permit cleaning and replacement removal of the filters 48 and access to the light bulb 22.

With the arrangement as described hereinabove in detail, the light bulb 22 is preferably energized continuously during use of the freezer F to provide heat sufficient to avoid accumulation of condensation of frost and moisture in the aperture 12, with the air filters 48 providing resistance to air flow so that there will be little or no air movement through or in and out the aperture during static conditions.

During the initial and each subsequent cooling cycle, the air in the freezer F will contract as it cools, tending to cause a lowering of the air pressure therein and a pressure differential with the atmosphere. Under this condition air will be drawn, due to the pressure differential, from the exterior through the aperture 22 into the freezer to balance the pressure. In so doing, the air passes through the filters 48 and is cleaned thereby. with the filters providing resistance to air flow to avoid excessive air movement and the light bulb 22 providing heat to raise or maintain the temperature of the air at a sufficient level to maintain the relative humidity low enough in the aperture to an extent that would cause an undesirable accumulation of frost or moisture, The heat from the light bulb 22 also importantly provides heat to minimize frost or moisture accumulation by condensation on the filters 48.

When the air in the freezer F is periodically heated to defrost the freezer interior, the air therein expands, creating a pressure differential with the atmosphere that causes air to flow through the aperture from the freezer interior to the atmosphere to equalize the pressure. During this condition the light bulb 22 and filters 48 serve the same purposes as described above with respect to the cooling cycle, but less significantly as the air flow is primarily from the cool interior to the warmer exterior so that the air temperature tends to rise and the relative humidity decrease to some extent even without the aid of the heat from the light bulb 22.

Air flow through the aperture 12 also takes place whenever the freezer door D is opened or closed, and for this circumstance the aperture 12 is preferably located adjacent the door D. As seen in FIG. 1, a location above the door D is preferred as it is less subject to obstruction and to air currents during otherwise static conditions.

The use ofa light bulb 22, being observable, advantageously provides a simple means of detecting when the unit is or is not working. The light from the bulb 22, being observed through the filters 48, allows easy inspection of the filters for excessive dirt or condensation that requires removal of the filters for cleaning or replacement.

A further advantage of the use of light bulb 22 is the light provided thereby in the interior of the freezer.

In the preferred embodiment illustrated, the pressure release port of the present invention is shown incorporated in a walk-in freezer F having a wall thickness of 4 inches. The aperture 12 is 4% inches high and 8% inches wide. The light bulb 22 is a 50 watt rough service bulb. The filters 48 have a face area of 46 square inches and are multiple layers of expanded aluminum meshfilter media of the type conventionally used as air filters in applications such as fans for kitchen stoves.

The foregoing specific dimensions and specifications, as well as the description of the preferred embodiment, are provided for the purpose ofillustration only and are not intended as limitations on the scope of the invention as various modifications and changes can be made within the scope of the present invention, which is intended to be limited only by the scope of the appended claims.

I claim:

1. A pressure release port for a walk-in freezer or the like comprising an aperture extending through a wall of said freezer, an electric light bulb mounted in said aperture, means for energizing said light bulb to create heat in said aperture for minimizing moisture and frost accumulation in said aperture, an air filter extending across said aperture to clean air passing through said aperture and to provide resistance to the free flow of air therethrough, thereby enhancing the heating effect of said light bulb therein.

2. A pressure release port for a walk-in freezer or the like according to claim 1 and characterized further in that said air filter is disposed across said aperture on one surface of said wall.

3. A pressure release port for a walk-in freezer or the like according to claim 2 and characterized further by another air filter extending across said aperture on the opposite surface of said wall with said light bulb between said filters.

4. A pressures release port for a walk-in freezer or the like according to claim 2 and characterized further in that said air filter is slidably mounted in an openended frame secured to said wall surface to permit cleaning and replacement removal of said filter and access to said light bulb.

5. A pressure release port for a walk-in freezer or the like according to claim 1 and characterized further in that said freezer has a door in a wall thereof and said aperture is disposed in said wall adjacent the door.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Pate t N 3,916,643 Dated November 4, 1975 v Inventor-( Edward A. Brown It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 44, after "coils" delete "and" and insert therefor are-; Column 1, line 61, delete "mositure" and insert therefor -moisture-; Column 4, line 49, delete "pressures" and insert therefor -pressure.

Signed and Scaled this tenth Of February 1976 [SEAL] Attest:

RUTH C. MASON C. MARSHALL DANN Attesling Officer (ommissiumr ofPatents and Trademarks 

1. A pressure release port for a walk-in freezer or the like comprising an aperture extending through a wall of said freezer, an electric light bulb mounted in said aperture, means for energizing said light bulb to create heat in said aperture for minimizing moisture and frost accumulation in said aperture, an air filter extending across said aperture to clean air passing through said aperture and to provide resistance to the free flow of air therethrough, thereby enhancing the heating effect of said light bulb therein.
 2. A pressure release port for a walk-in freezer or the like according to claim 1 and characterized further in that said air filter is disposed across said aperture on one surface of said wall.
 3. A pressure release port for a walk-in freezer or the like according to claim 2 and characterized further by another air filter extending across said aperture on the opposite surface of said wall with said light bulb between said filters.
 4. A pressures release port for a walk-in freezer or the like according to claim 2 and characterized further in that said air filter is slidably mounted in an open-ended frame secured to said wall surface to permit cleaning and replacement removal of said filter and access to said light bulb.
 5. A pressure release port for a walk-in freezer or the like according to claim 1 and characterized further in that said freezer has a door in a wall thereof and said aperture is disposed in said wall adjacent the door. 